Heat exchanger

Claim 1

A heat exchanger for optimizing the room heating efficiency of a typical fireplace comprising a plenum including a radially extending housing having an upwardly sloped top wall and a downwardly sloped bottom wall connected at a closed apex, said housing including respective air inlet and air outlet passages, and a casing for removably mounting said plenum a predetermined distance above a fireplace hearth, said casing locating the rearward end of said air inlet passage provided in said plenum angularly downwardly towards said hearth, said apex of said plenum housing defining a narrow flue passage with a rearward wall of said fireplace for expulsion of effluent gases, said plenum and said casing being discrete and separable from said fireplace, said casing overfitting said fireplace hearthway and said plenum being fixedly connected thereto, said casing including an air inlet port overfitting said air inlet passage of said plenum housing, an air outlet port overfitting said outlet passage of said plenum housing, a draft port for drafting a fire provided on the hearth of said fireplace, means for access to said fireplace hearth, and an interiorly extending tongue foreshortened from said apex thereof, said tongue thereby defining with said top and bottom walls of said housing said air inlet and air outlet passages.